Unintended Consequences Of Raising Rear Ride Height?

[jeremy556]

On my 02 VFR, I currently have the front end at stock ride height, and the rear end raised 10mm from stock via ride height adjustment of my Ohlins shock. I have 30mm front and rear of sag.

A couple weeks ago I did a ride 2 up and had to adjust the preload way up to avoid dragging a peg in every turn. I took a ride solo after that without adjusting the preload and noticed I could go a lot faster without dragging parts everywhere. So tonight, I added another 15mm of ride height to the rear end (25mm higher than stock now) and set my sag (now at 28mm with no preload).

I realize that this will transfer weight to the front end making the rear more likely to lose traction, but does anyone of anything else to look out for? I will take it for a short shake down run locally tomorrow before a trip to the mountains later this week.

ETA: Yes, I realize headshake could also be a problem with more front end weight bias/less rake/less trail. I will do a few wheelies to test it out :fing02:

[marid2apterbilt]

:comp13:

How is the turn-in or handling with it raised that high :fing02:

[jeremy556]

:comp13:

How is the turn-in or handling with it raised that high :fing02:

Dunno, I'll tell you tomorrow.

I would imagine it may be to the point of instability.

[SEBSPEED]

I know your biggest gripe with the viffer is ground clearance, but you've also got long legs... have you given any thought to custom rearsets? Not necessarily something off the shelf, something designed for you?

Good luck with the settings. :fing02:

[jeremy556]

Not really. I hate replacing my expensive ceramic Sidi toe sliders, but I hate dragging my headers and fairings on the ground more. So rearsets wouldn't give me much for ground clearance while decreasing my comfort level, though I have looked closely at the Thurn adjustable peg mounts.

[Baileyrock]

Jeremy,

I was playing with this some time back where I raised the rear(Ohlins) a bunch and also dropped the forks 10mm too.

What I thought happened was that it was quicker stearing, but started requiring More bar input. I went back.

Let me know what you find. :fing02:

[Beck]

I have my forks dropped 13mm and my rear end shimmed up by at least 24mm for a long time already. Haven't had any rear traction problems with this setup on my 4th gen, even with the bad handling Dunlops that I just replaced with the awesome PR2CTs.

Beck

95 VFR

[jeremy556]

Jeremy,

I was playing with this some time back where I raised the rear(Ohlins) a bunch and also dropped the forks 10mm too.

What I thought happened was that it was quicker stearing, but started requiring More bar input. I went back.

Let me know what you find. :fing02:

My front end is stock height. I could care less about quick steering or more input needed, I am mainly just looking for more ground clearance = faster.

I should probably just get a supermoto. :fing02:

[jeremy556]

I have my forks dropped 13mm and my rear end shimmed up by at least 24mm for a long time already. Haven't had any rear traction problems with this setup on my 4th gen, even with the bad handling Dunlops that I just replaced with the awesome PR2CTs.

Beck

95 VFR

That is good to hear. If this goes well, I may bump it up to 30mm in the rear, as the move from 0-10mm in the rear was a huge improvement. I need to find some longer forks.

[jeremy556]

Jeremy,

I was playing with this some time back where I raised the rear(Ohlins) a bunch and also dropped the forks 10mm too.

What I thought happened was that it was quicker stearing, but started requiring More bar input. I went back.

Let me know what you find. :fing02:

I'll show you if you make it out to NC and NGA this week.

[HispanicSlammer]

Just raise up the front end a few mm as well to keep bias balanced between front and back, added effect being you get more clearance.

[jeremy556]

Just raise up the front end a few mm as well to keep bias balanced between front and back, added effect being you get more clearance.

Can't raise the front end 25mm, would if I could, unless, maybe having the clipon not fully on the fork tube... I would have thought of that as a hard limit, but now that I think about it, the clipons don't really need much clamping area...

[JTG]

To quote someone far more knowledgeable than I am about this;

This is in regards to someone asking a question about raising the rear or lowering the front to make the bike steer quicker

"...another factor to consider is swingarm angle and squat: Raising the whole bike increases the swingarm angle, resulting in more antisquat. Squat is the tendency of the bike to transfer weight to the rear end under acceleration. Antisquat is the mechanical advantage of the chain/swingarm relationship that offsets that tendency, allowing just enough weight transfer to give optimum traction at both the front and rear ends. With too much squat, the bike will run wide on corner exits as the front tire loses traction. You can raise the rear end (or the whole bike) to fix this. With too much antisquat, the rear tire will tend to spin up abruptly and snap sideways; lower the rear end (or the whole bike) to address this." -Andrew Trevitt-

So in short he's saying it's a matter of losing traction front or rear because of the angle of the swingarm when the ride height is changed.

Anyway have fun tinkering with your bike :fing02:

[Guest]

Much of this info is from the Traxxion suspension video. I don’t have anything positive to say about Traxxion’s business practices, but they do have some good knowledge.

The "theoretically ideal" swingarm angle is 12.7 degrees. If the swingarm is flat, a low swingarm angle, the squat is excessive and thrust is straight back on the hub, this doesn't push the tire DOWN to the tarmac, just back. If the swingarm is steep, a high swingarm angle, the thrust is pushing DOWN on the hub rather than BACK on the hub and wheel spin is the usual result, the bike lifts, wheel spins without that bothersome forward thrust thing.

This should be measured with a protractor with the bike on it's tires with the suspension topped out (no weight on the tires at all) on level ground. This should be measured across the swingarm center pivot point and the center of the hub. I use a digital protractor from work, but people usually use a roof pitch gauge to check this. I did this with my race bike and started at 12.7, but it gave me quite a bit of headshake on the straights. Since I had the front end at stock height I had to shorten the shock a bit to get the shake to go away, so I backed it off to 12.3. If I had the machining capability to make some offset swingarm inserts for the frame I could raise the front of the swing arm in the frame have the ideal angle while maintaining the correct front rake/trail geometry.

I have my 4th gen VFR raised up as high as the stock dogbones will allow, but I've never measured it. The front height is stock. I haven’t had any problems with it, although I wish I had a steering damper for it. It's a little "twitchy" :fing02:

[skuuter]

"My 2 cents"........raising the rear does not necessarily make you lose rear traction unless you reached a really ridiculously excessive amount. Chain angle, and swingarm pivot points on stock motorcycle frames will not really allow this point to be reached. Raising the rear actually increases the available weight transfer under power which makes the point of maximum rear traction higher. A raised rear bike will keep transfering traction to the rear wheel longer than a lowered bike.

Now, as BR stated, lowering the front ride height changes the "static" weight riding on the front wheel, making it feel "heavier" requiring more bar input to turn. Because of the changed trail angles, etc., lowering the front does give it quicker turn in. "MY" ideal set up on a bike would be a raised rear (obviously not possible because of "personal height issues") with a fairly soft rear spring and a lot of rebound dialed in, a lowered front end with heavy springs. Initial turn-in would be quick with moderate bar input, then a very light front "feel", and lots of rear-forward bite under power exiting the corner. Apex ride height should still be adequate to allow lotsa' lean before parts touchdown starts........ :fing02:

EDIT: Spent many years setting up race cars on wheel scales, adjusting ride heights, spring rates, trailing bar and control arm angles, etc............... :fing02:

[jeremy556]

I took it out this morning for a ride around town to test it out. Initial results: inconclusive. Bike has no bad manners that I experienced. Handling is much better and more neutral now, but I just changed tires from some worn out Qualifiers to new Pilot Powers.

[SEBSPEED]

Now with more miles, got any more feedback on this? You seemed to be doing pretty damn well with it last week!

[Guest]

I've raised the rear of my VFR about 25 mm and dropped the front end about 10 mm. Really makes the front feel planted in the turns.

What's the relationship of chicken strip widths? Taking a rear tire all the way to the edge (which I suspect you do) and having about half an inch of chicken strip on the front means you have too much rear weight bias. Raise the rear until the front tire has about a quarter inch or less chicken strip than the rear.

It's been my experience that just about all bikes respond positively to having the rear end raised (SV650, ZRX1100, ST1300, KTM Duke II).

[VFR Capt.Bob]

Just raise up the front end a few mm as well to keep bias balanced between front and back, added effect being you get more clearance.

Can't raise the front end 25mm, would if I could, unless, maybe having the clipon not fully on the fork tube... I would have thought of that as a hard limit, but now that I think about it, the clipons don't really need much clamping area...

Is'nt there a circlip at some point on the fork tube as a saftey factor to ensure the clip on stays on? I wouldn't mess with this saftey feature. I think Doug Chandler had a big crash on the cork screw when his clip on came off in his hand. A true WTF moment I'd like to avoid.

[jeremy556]

Now with more miles, got any more feedback on this? You seemed to be doing pretty damn well with it last week!

Not yet, only had the one ride last Wednesday. I wasn't really quite used to it, so it didn't feel quite "right," need a few more rides on it. Also, with the new tires, I can't make any fair comparison. I did turn it up a couple of times on Wednesday, and I noticed that I didn't touch down a peg a single time (or more importantly, a $40 Sidi ceramic toe slider), where I would have with my previous setup, so that is a definite plus.

Depending on weather I hope to do my normal 500 mile loop sometime in the next few days to give it a proper shake down.

[jeremy556]

What's the relationship of chicken strip widths?

Depends on the riding I am doing. If it is mostly more relaxed sweepers and higher speed stuff, I will have maybe 1/8th of a strip on the front. If I do any tight twisty stuff the front strip will be gone. I usually get rid of the rear strip leaving my driveway

I haven't looked at the tires since before my ride last week, but with my old setup I would have quite a bit of front strip left.

[jeremy556]

Is'nt there a circlip at some point on the fork tube as a saftey factor to ensure the clip on stays on? I wouldn't mess with this saftey feature. I think Doug Chandler had a big crash on the cork screw when his clip on came off in his hand. A true WTF moment I'd like to avoid.

Yes there is, and that is what I was thinking of as the hard limit. I am not too concerned with it; the pinch bolt is plenty to keep the clipon in place, and my track bike with aftermarket clipons didn't have a circlip at all.

[cozye]

damn boy, when you just going to get a proper bike fast enough for you :fing02:

[jeremy556]

When I can afford to; i.e. probably never :fing02:

I'm sure the VFR can be hustled around a lot faster than I am capable of anyway.

[marid2apterbilt]

So any more updates on Handling changes etc..

[jeremy556]

So any more updates on Handling changes etc..

Nope. Haven't ridden since the last time I saw you.

Don't expect any real updates anyway as I changed tires at the same time, so any handling differences are inconclusive. All I can say with any certainty is there is more ground clearance. I didn't scrape a peg once during that ride even when I did a loop of the Richard B Russel and 129/Blood Mountain solo. Usually, I would have noticeably worn down my toe sliders.